Phobos is one of Mars's moons (Credit: Nasa/JPL-CalTech/University of
Arizona)

The monolith appears to be a large boulder, variously described as building-sized or 90m tall. It stands in a desolate, featureless region of Phobos, which probably
makes the monolith seem even more impressive.

Other spooky features, like the infamous face on Mars, do not seem quite so
unusual when you take a closer look

Given that Phobos is so small, there is another potential source for impact
debris on its surface. Such debris might actually be flung at Phobos from the
surface of Mars, as the Red Planet is hit by asteroids from time to time.

Phobos is just about the most mysterious body in the known Solar System

Alternatively, the Phobos monolith might not have formed during an impact.
It could be a rare chunk of the moon's solid bedrock, poking up through a
surface that is otherwise mostly strewn with loose debris.

Phobos is one of two tiny moons orbiting Mars, the other being Deimos. It
is not really clear how they got there.

Both are small and irregular in shape, which makes them look a little like
asteroids that fell into Mars's gravitational clutches long ago. But the moons
orbit Mars in a way that is incompatible with this "snatched asteroid"
idea.

Eventually, the large moon and all but two of the small moons orbited so
close to Mars that they disintegrated

An alternative is that they formed from the same material that Mars did
when the planet coalesced billions of years ago. However, precise astronomical
measurements reveal that Phobos has a much lower density than typical Martian
rock.

That leaves a third idea: Mars suffered a devastating impact with a large
protoplanet long ago, which generated the two moons.

AWAKENING FOR ALL!!!

The Jerry Wills Show

The Jerry Wills Show with Kathy Wills begins broadcasts again in September.The start date will be announced on FaceBook, through our newsletter, and through other social media outlets. We look forward to connecting with our friends soon!